Pressure vessel and method of making same



19 62 E. l. VALYl 3,062,403

PRESSURE VESSEL AND METHOD OF MAKING SAME Original Filed March 12, 19572 Sheets-Sheet l L 9 kl0 26 INVENTOR. EMERY Z VAL Y/ Nov. 6, 1962 E. 1.VALYl PRESSURE VESSEL AND METHOD OF MAKING SAME 2 Sheets-Sheet 2Original Filed March 12, 1957 AMI l INVENTOR F/YEEY J: V44 Y/ ATTORNEYiinited States Patent 1 Claim. (Cl. 22072) This invention relates toseamless vessels and has for an object to provide a novel and improvedproduct of that type.

This application is a division of my co-pending application Serial No.645,592 filed March 12, 1957, now Patent No. 2,957,234.

An object of this invention is to provide a novel and improved vesselwherein welding and annealing the vessel is eliminated or at leastsubstantially reduced.

Another object is to provide closed end vessels having integral externalfins or ribs.

Various other objects and advantages will be apparent as the nature ofthe invention is more fully disclosed.

Closed vessels, such as containers used for the transporting of liquidsand gases, or as containers in the chemical industry, or as pressurevessels, are usually fabricated by extensive use of welding. Thisentails the use of highly skilled labor and extensive and completeinspection of all weld areas. In addition in many desirable alloys thecharacteristic of the parent metal is altered irreversibly in the entireheat affected area which results in undesirable physical properties.

To produce the vessel of this invention, a casting containing arefractory core is first made, shaped to produce a chamber in thecasting. The refractory core may be provided with one or more metalsupports which position the core accurately in the mold and which areadapted to fuse into the metal of the casting in the casting step, orwhich are adapted to become integral with the metal of the castingduring the subsequent rolling thereby constituting closures or partialclosures for the core chamber in the casting.

After the casting is removed from the mold in which it was made it isrolled in one or more directions to form a flat sheet in which the corechamber is flattened to the form of a thin slit having a size and shapesuited when inflated to produce the desired vessel. The initial stagesof the rolling may be made with the casting hot and the final stages maytake place with the sheet cold so as to impart the desired metallurgicalcharacteristic to the rolled sheet. Welding of the opposite walls of thecore chamber is prevented during rolling, as for example by allowing therefractory core to disintegrate and to form a coating.

If the flattened chamber is closed at both ends a hole is drilled intothe flattened chamber and fluid pressure is introduced to expand theWalls to the shape of the desired vessel. The portion of the sheetbeyond the flattened chamber forms fins or ribs extending along oppositeside walls of the vessel and around or partly around the closed end orends. These fins or ribs may serve as reinforcing elements or assupports or attaching means for other equipment. The fins or ribs may beremoved or partly removed where not required on the finished vessel andthey are reduced by partial removal to a bead at the closed ends.

If in producing the casting the refractory core extends to a pointbeyond the mold cavity, the vessel will be closed at one end only andwill be open at the other end. In this case expanding the flattenedchamber after the rolling operation can be done by hydraulic ormechanical means, or a combination of both.

The characteristics of the vessel and the steps in forming the vesselwill be better understood from the following description, taken inconnection with the accompanying drawings in which a specific embodimenthas been set forth for purpose of illustration.

In the drawings:

FIG. 1 is a transverse section through a mold showing a casting andcores therein embodying the present invention;

FIG. 2 is a detail view of the core used in the mold of FIG. 1;

FIG. 3 is a detail view of a similar core having a metal tip at one endonly;

FIG. 4 is a detail view of a similar core having an intermediate metalsupport;

FIG. 5 is a transverse section through the casting of FIG. 1;

FIG. 6 is a broken perspective view of the casting after rolling in onedirection;

FIG. 7 is a similar broken perspective view of the casting after rollingin two directions to form a flat sheet;

FIG. 8 is a longitudinal section of a vessel made from the rolled sheetof FIG. 7;

FIGS. 9 and 10 are transverse sections through the vessel taken on thelines 9-9 and 10-10 respectively of FIG. 8;

FIG. 11 is a perspective view of a vessel made from the rolled sheet ofFIG. 7; and

FIG. 12 is a partial longitudinal section showing a pair of axiallyaligned vessels as produced by the use of a core shaped as that of FIG.4.

Referring to the drawings more in detail, FIG. 1 shows a casting 10 castin a mold 11 around a refractory core 12 having metal tips 14 and 15.The metal tips 14 and 15 are formed with projections 16 which seat inrecesses 17 in the mold to hold the cores in place during the pouringoperation. The metal tips 14 and 15 fuse into the poured metal or becomeintegral with the metal of the casting during the subsequent rollingoperation to form in the casting a closed core chamber 18.

A core of the above type is shown in FIG. 2. FIG. 3 shows a similar corewith the metal tip at one end only. If this core is used instead of thecore of FIG. 2 the casting will have a core chamber 18 which is closedat one end and open at the other.

FIG. 4 shows a refractory core 12 similar to FIG. 2 having a centralmetal support 19. If the core of FIG. 4 is used the core chamber 18 willbe divided axially into two separate parts and will have closed ends. Ifthe metal tips 14 and 15 are not used, open end core chambers will beproduced. The type, size and shape of the core is selected to produce avessel of the desired configuration.

The casting 10 after removal from the mold is rolled transversely byknown technique to form the sheet 20 of FIG. 6 with walls 21 and 22separated by a slit 23 in the area of the now flattened core chamber.The core may be still in place as shown in FIG. 5 during rolling.

The sheet 20 is then rolled longitudinally to extend it to the sizerequired for the vessel or vessels to be formed, as shown in FIG. 7. Ofcourse the order of the longitudinal and transverse rolling may bereversed or alternated as desired to shape the final sheet to therequired form. The transverse rolling may be omitted if not required.

According to the example shown here, the core 12 is crushed to powderand forms an anti-weld material to prevent the walls 21 and 22 fromwelding together. Other means to prevent such welding are known to thoseskilled in the art of rolling metal.

The sheet of FIG. 7 is now opened up to form the vessel of FIGS. 8 to11. For this purpose a hole is drilled into the flattened chamber orslit 23 between the walls 21 and 22 and fluid pressure is introduced toforce the plies apart and form them into the desired contour, forexample into the contour of a closed vessel having side walls which maybe subsentially cylindrical at at least their central portions, as shownin section in FIG. 10, and which taper or are flattened towards theends, as shown in section in FIG. 9.

If one end of the slit 23 is open, as would be produced by the use ofthe core of FIG. 3, the walls may be expanded by fluid pressure or atool may be introduced between the walls for expanding them into theform of an open end vessel, or a combination of hydraulic and mechanicalmeans may be used.

The areas of the sheet beyond the flattened slit 23 produce longitudinalfins 24 which extend along the side walls of the vessel and form endfins 25 which are trimmed or partially removed before expanding theflattened chamber to leave beads 26 which extend across the closed endor ends of the vessel. Such removal of the end fins 25 limits therestraining effect which these fins would have upon the shaping of thewalls of the vessel during expansion. The fins 25 should 'be trimmed toan extent such that the thickness of the head 26 from the bottom of theslit in the rolled strip to the edge of the bead is of the order of thewall thickness of the vessel as indicated in FIGS. 8 to 11. If the head26 were made narrower than the walls, the walls would be weakened atthis point. On the other hand, if the head is made substantially thickerthan the final wall thickness of the vessel, it would impart anundesirable resistance to the forming operation. The fins or ribs 24 mayserve as structural reinforcing members and also provide means forattaching supports or auxiliary equipment without the necessity forwelding onto the walls of the vessel.

A plurality of vessels may be made from a single casting by making a rowof parallel core chambers in the casting. When rolled as above describedand expanded a row of parallel vessels joined by intermediate webs areprovided. The webs may be severed for separating the individual vesselsif desired.

A longitudinally divided vessel may be made by forming a pair ofvertically aligned core chambers in the casting. When this structure isrolled and expanded a closed vessel is formed having a longitudinaldividing wall separating the interior into two chambers.

When the core of FIG. 4 is used in making the casting a pair of axiallyaligned vessels is produced joined by webs 34 as in FIG. 12. The joiningweb 34 may be partially removed or notched to reduce the restraininginfluence thereof as in the case of the end fins 25 of FIG. 8. Of coursemore than two such axially aligned vessels may be made by introducing aplurality of intermediate metal members into the core.

These vessels may be severed through their joining webs 34 to formindividual closed end vessels. Of course the closed end vessels may besevered transversely at any intermediate point to form a pair of vesselsopen at one end.

In any of the embodiments it is to be noted that the finally formedvessel is entirely integral and has the metallurgical characteristicsproduced by the rolling operations without local areas' of differingcharacteristics such as would be produced by welding.

In the form shown in FIG. 8 the diameter of the vessel is shown asdecreasing from the oval end section of FIG. 9 to the cylindricalcentral portion of FIG. 10. It is understood of course that this shapemay be varied as desired by suitably shaping the core and that variousintricate or irregular shapes of vessels may also be produced bycorrespondingly varying the contour of the core. The size and locationof the openings may also be varied by suitable variations in theposition and shape of the core. Such openings may be at the end or atthe side, or a plurality of such openings may be formed in a singlevessel as desired. The vessel may of course be made in various sizes,from those suitable for small pressure bottles to the dimensions oflarge boilers, autoclaves, or reactors.

What is claimed is:

An integral metal vessel having side walls and at least one end wall, apair of fins extending longitudinally along opposite side walls and abead having a minimum radial thickness of the order of the thickness ofsaid walls extending around the end wall, said bead joining and forminga continuation of said fins, said walls, fins and bead being seamlessand integral and all having the characteristics of rolled metal.

References Cited in the file of this patent UNITED STATES PATENTS377,317 Marshall Jan. 31, 1888 2,690,002 Grenell Sept. 28, 19542,857,660 Staples Oct. 28, 1958 2,859,509 Adams Nov. 11, 1958 FOREIGNPATENTS 4,794 Great Britain Feb. 17, 1894 190,585 Great Britain Dec. 28,1922

